Different metals respond quite differently to being heated. Copper is a hard, pinky-brown metal that is low in the reactivity series. When heated in air its surface gets covered in a layer of black copper oxide. It melts at 1080 °Celsius so won’t melt in the 750 degrees possible with a Bunsen burner. It is an excellent conductor of electricity and heat so is used in electrical wiring and for plumbing pipes. Its colour adds lustre to brass which is used for decorative fittings and coins.
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Lead is a soft, dense, unreactive metal with a relatively low melting point. Its Latin name is plumbum which is where we get the English words plumber, plumbing and plumb line. It melts at about 330 Celsius so it can be easily melted in the lab. It is very toxic though so you should make sure that the room is well ventilated and try to avoid inhaling any fumes it may emit. In the following video you can see that under the surface layer of dull grey oxide lead is a typical shiny metal – really rather beautiful when molten.
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Magnesium is a reactive, group II metal (i.e. the second most reactive group of metals on the periodic table). It burns brightly in air to leave a very white, solid oxide behind. Magnesium oxide reacts with water to produce a mild alkali (magnesium hydroxide) which is used in indigestion remedies to neutralise the acid in your stomach. Magnesium has a low density so it can be mixed with aluminium to make lightweight alloys that are useful in aircraft manufacture and high performance cars.
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Magnesium is more reactive than carbon so it can burn in carbon dioxide. It rips the oxygen away from the carbon (it displaces the carbon). It will also burn when encased in dry ice which is solid carbon dioxide made by cooling it down below -79 °C.
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Questions…
- Name a metal higher in reactivity than lead but lower than magnesium.
- Which of the metals above would be best for…
- making water pipes
- water-proofing a church roof
- reacting with acid to make hydrogen
- making inexpensive jewellery
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